19 Common Grammar Mistakes And How to Avoid Them

19 Common Grammar Mistakes (And How to Avoid Them)

If you want to get better at writing, grammar is one of the first things you should learn. Sure, you may know the basics, but there are several common grammar mistakes that you might still make on occasion. Whether it’s excessive passive voice use, subject-verb agreement issues, or confusing one word for another, these grammar mistakes can take your writing from an A to a D.

A writing tutor can help you work through these grammar-related challenges and enhance your writing quality. We’ve also put together some of the most common grammar mistakes to give you an idea of what to avoid in the future.

1: Subject-verb agreement issues

People often make the mistake of using a verb that doesn’t agree in number with the subject of the sentence. This is understandable because there are some intricacies to the rule, with the main ones being:

The subject and the verb should agree in number and in person

Examples:

  1. The manager and a few employees are having lunch in the cafeteria.
  2. The manager, along with a few employees, is having lunch in the cafeteria.

Use a plural verb for compound sentences joined using the word “and”

However, this doesn’t apply when “and” is separating terms that refer to one person and when words like “each,” “every,” or “many” come before it.

Examples:

  1. My cat and my dog are best friends.
  2. My dog and best friend (referring to the dog) is coming with me on a hike.
  3. Every dog and cat has a unique personality.

For compound sentences joined using the word “or” or “nor,” make sure the verb agrees to the noun closest to it

Examples:

  1. My husband or my best friends are planning my birthday party.
  2. My husband or my best friend is planning my birthday party.

Use a plural verb when “a number” is the subject, but a singular verb when “the number” is the subject

Examples:

  1. A number of friends are coming to my party.
  2. The number of friends coming to my party has increased.

Use a plural verb when the phrase “one of those” precedes a plural noun

Example:

  1. She’s one of those people who are never late.
  2. He’s one of those (writers or scientists or whatever) who state it best.”

2: Verb tense shift

Another common grammar mistake is the random shift of tenses in the same sentence. Stick to the same tense throughout your writing to avoid confusing your readers. Depending on whether you have to use APA or MLA format, you need to present your research in either past or present tense. A bit of English tutoring can help you learn grammar and work through these issues to improve your writing skills.

Incorrect: She waves at me and then I waved back with gusto. Correct: She waves at me and then I wave back with gusto (or she waved at me, and then I waved back with gusto).

3: Comma splice

A comma splice is when you join two independent sentences using a comma when you should separate them with a coordinating conjunction or a period.

Incorrect: She cried a lot, her eyes were puffy. Correct. She cried a lot. Her eyes were puffy. Correct. She cried a lot, so her eyes were puffy.

4: Unnecessary comma

We’ve all probably struggled with punctuation errors such as using a comma when it’s not needed. You should never use a comma to:

Separate an independent clause from its dependent clause

Incorrect: He quit his job, because he was burnt out. Correct: He quit his job because he was burnt out.

Separate the verb from its direct object

Incorrect: Stop cutting, trees. Correct: Stop cutting trees.

Separate elements that have a coordinating conjunction joining them

Incorrect: She wants to become a doctor, or a teacher. Correct: She wants to become a doctor or a teacher.

5: Missing comma

On the other end of the spectrum, some people also fail to use a comma where it’s crucial. To avoid future punctuation errors, always use a comma in the following instances:

After an introductory element

Incorrect: In case you wanted to know I’m happy to join the group. Correct: In case you wanted to know, I’m happy to join the group.

For separating two independent clauses in a compound sentence

Incorrect: She was happy and she loved to dance. Correct: She was happy, and she loved to dance.

6: Lack of parallelism

Every part of your sentence should be parallel in form so they are grammatically similar and easier to read.

Incorrect: She enjoyed swimming, cycling, and to paint. Correct: She enjoyed swimming, cycling, and painting. Correct: She liked to swim, cycle, and paint.

7: Run-on sentences

A run-on sentence is when you join two complete sentences without any coordinating conjunction or punctuation.

Incorrect: John gave her a bouquet of roses for their anniversary however she prefers wildflowers. Correct: John gave her a bouquet of roses for their anniversary. However, she prefers wildflowers.

8: Excessive use of passive voice

While passive voice isn’t grammatically incorrect, it can overcomplicate your writing and make it difficult for readers to understand. When there’s a simpler, active voice alternative, always use it instead of passive voice.

Passive: Those stones were picked up by Sandy from the beach last summer. Active: Sandy picked up those stones from the beach last summer.

9: Dangling modifiers

Dangling modifiers are among the most common grammar mistakes. This is when you use a descriptive phrase that doesn’t apply to the noun immediately following it. As such, it can disrupt your writing flow and make it awkward and confusing.

Incorrect: After sitting in the fridge for weeks, Kim finally threw the stale sandwich. Correct: Kim finally threw away the stale sandwich after it had been sitting in the fridge for weeks.

10: Incomplete comparisons

This common grammar mistake occurs when you use comparative verbs without specifying what you’re comparing the subject against.

Incorrect: This neighborhood is safer and more peaceful. Correct: This neighborhood is safer and more peaceful than most neighborhoods in the city.

11: Possessive nouns

While most possessive nouns have an apostrophe, some people may get confused about where to add the apostrophe. This is a critical mistake because your apostrophe placement can change the whole meaning of the sentence.

Example: All of the girl’s baskets were red.

While “all” implies that there’s more than one girl, the apostrophe placement suggests that there’s just one. In general, plural nouns should have an apostrophe after the “s”, like in, “All of the girls’ baskets were red.”

If you want to say that there’s one girl who has multiple baskets that are all red, the sentence should be, “The girl’s baskets were all red.”

Even in singular nouns that end with an “s,” the apostrophe should come after the “s” like in “the witness’ statement.” In case of singular nouns that do not end with an “s,” the apostrophe comes before the “s.” For example: “the girl’s baskets.”

12: Your vs. you’re

One of the most common grammar mistakes include commonly-confused words such as “your” and “you’re.” Here’s the simplest way to differentiate between the two:

Your – A possessive pronoun

Incorrect: We’ll need to contact you’re next of kin. Correct: We’ll need to contact your next of kin.

You’re – A contraction of “you are”

Incorrect: Your next in line for the throne. Correct: You’re next in line for the throne.

So, the main difference is in owning something vs. being something.

13: There, their, and they’re

Another common confusion is between “there,” “their,” and “they’re.” Here’s the simplest way to differentiate between the three:

There – Meaning in or at a certain place

Incorrect: Get the book from over their. Correct: Get the book from over there.

Their – Possessive pronoun

Incorrect: I bought they’re house. Correct: I bought their house.

They’re – Contraction of “they are”

Incorrect: There already here. Correct: They’re already here.

The main difference is in something being in/at a certain place, owning something, and being something.

14: Its or it’s

People often get confused about the right time to use its or it’s. Here’s how you can avoid one of the most common grammar mistakes and differentiate between the two:

Its – Possessive pronoun

Incorrect: This app holds it’s own against the competition. Correct: This app holds its own against the competition.

It’s – Contraction of “it is”

Incorrect: Its no longer important to me. Correct: It’s no longer important to me.

15: Lay vs. lie

Surprisingly, this grammar mistake is extremely common with native English speakers. Here’s how you can avoid misusing the two:

Lay – The act of placing an object somewhere

This verb requires an object in the sentence, like in, “I lay my head on the pillow.”

Lie – Describes something that’s moving on its own or is already in position.

Lie is intransitive verb and therefore, doesn’t need an object.

Incorrect: She’s laying down for a nap. Correct: She’s lying down for a nap.

Incorrect: I’m going to lay down for a bit. Correct: I’m going to lie down for a bit.

16: Could of and could have

Since they sound very similar, people often use “could of” instead of “could have.” Remember that “could of” is never correct, and you should always use “could have” instead.

17: Me, myself, and I

Another common grammar mistake involves the confusion between the first person pronouns – “me,” “myself,” and “I.” Some people will even assume that you should always use “I” as a first person pronoun following “and.” However, that’s not always correct depending on whether the pronoun is an object or a subject. Here’s how you can differentiate between the three:

Me – Use this pronoun as an object of the verb.

Example: My aunt sent gifts for my sister and me.

Myself – This is a reflexive personal pronoun and should never be the subject of a sentence.

Example: I bought this for myself.

I – Use this pronoun as an object of the verb.

Example: Sally and I are going to a party.

18: Then vs. than

Since they sound and look fairly similar, people sometimes misuse “then” and “than.” Here’s a quick guide to help you differentiate between the two:

Then – This adverb situates actions in time.

Examples:

  1. Things were so much better then.
  2. I made breakfast, and then I left for work.

Than – This is a conjunction that helps make comparisons.

Example:

  1. Chris is a better climber than Steve.
  2. This year is turning out to be worse than last year.

19: Whom vs. who

The misuse of “whom” and “who” is another tricky issue that a lot of people struggle with. Let’s take a look at the main differences between the two:

Whom – Used for the person that’s receiving something or on the receiving end of something

Examples:

  1. To whom did you send the letter?
  2. Whom did they choose for the role?

Who – Used for identifying a living pronoun

Examples:

  1. Who made these cookies?
  2. I’m the person who made those cookies.

Keep learning

These are just some of the most common grammar mistakes that you should avoid if you want to improve your writing. We may be unable to cover everything in a single post, so we recommend working with a writing tutor for a more thorough lesson. These tutors can help you learn grammar, brush up on your writing skills, and even learn how to write essay outlines for your research papers.

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